Synthesis and sintering of nano-sized forsterite prepared by short mechanochemical activation process

2016 ◽  
Vol 678 ◽  
pp. 290-296 ◽  
Author(s):  
Mohammad Sadegh Abdi Maghsoudlou ◽  
Touradj Ebadzadeh ◽  
Zahra Sharafi ◽  
Marziyeh Arabi ◽  
Karim Rostami Zahabi
Keyword(s):  
Mechanochemical Activation ◽  
Activation Process

Structural, Magnetic and Hyperfine Properties of Molybdenum Dioxide-Hematite Mixed Oxide Nanostructures

MRS Advances ◽  
2018 ◽  
Vol 3 (47-48) ◽  
pp. 2887-2892
Author(s):  
Richard Trotta ◽  
Felicia Tolea ◽  
Mihaela Valeanu ◽  
Lucian Diamandescu ◽  
Agnieszka Grabias ◽  
...  
Keyword(s):  
Ball Milling ◽  
Milling Time ◽  
Mechanochemical Activation ◽  
Magnetic Measurements ◽  
Activation Process ◽  
Zero Field ◽  
Molybdenum Dioxide ◽  
Nanoparticle System ◽  
Ball Milling Time ◽  
Field Cooling

ABSTRACTMoO2-Fe2O3 nanoparticle system was successfully synthesized by mechanochemical activation of MoO2 and α-Fe2O3 equimolar mixtures for 0-12 hours of ball milling time. The study aims at exploring the formation of magnetic oxide semiconductors at the nanoscale. X-ray powder diffraction (XRD), Mössbauer spectroscopy and magnetic measurements were used to study the phase evolution of MoO2-Fe2O3 nanoparticle system under the mechanochemical activation process. The Mössbauer studies showed that the spectrum of the mechanochemically activated composites evolved from a sextet for hematite to sextet and a doublet upon duration of the milling process with molybdenum dioxide. Recoilless fraction was determined using our dual absorber method and was found to decrease with increasing ball milling time. Magnetic measurements recorded at 5 and 300 K in an applied magnetic field of 50,000 Oe showed the magnetic properties in the antiferromagnetic and canted ferromagnetic states. The Morin transformation was evidenced by zero-field cooling-field cooling (ZFC-FC) measurements in 200 Oe and the transformation characteristic temperatures were shifted to lower values.

Europium Oxide-Hematite Magnetic Ceramic Nanoparticles

MRS Advances ◽  
2015 ◽  
Vol 1 (3) ◽  
pp. 215-220 ◽  
Author(s):  
Monica Sorescu ◽  
Lucian Diamandescu ◽  
John DiGnazio ◽  
Tianhong Xu
Keyword(s):  
Milling Time ◽  
Mechanochemical Activation ◽  
Phase Evolution ◽  
Milling Process ◽  
Europium Oxide ◽  
Activation Process ◽  
Solid Solution Formation ◽  
Biomedical Sensing ◽  
Solution Formation ◽  
Nanoparticle System

ABSTRACTNanoparticle system with the composition xEu2O3-(1-x)α-Fe2O3 (x = 0.1 and 0.5) was successfully synthesized by mechanochemical activation of Eu2O3 and α-Fe2O3 mixtures for 0-12 hours of ball milling time. The study is of relevance to catalysis, biomedical, sensing and energy-related applications. 57Fe and 151Eu Mössbauer spectroscopy were used to investigate the phase evolution, solid solution formation and hyperfine parameters of xEu2O3-(1-x)α-Fe2O3 nanoparticle system under the mechanochemical activation process. The 57Fe Mössbauer studies showed that the spectrum of the ball milled samples evolved from a sextet for hematite to sextets and a doublet upon duration of the milling process with europium oxide. This indicated the formation of the EuFeO3 perovskite for large x values and long milling times. The 151Eu Mössbauer investigations showed that the isomer shift decreased with increasing milling time for all molar concentrations employed.

Modifying the Sorption Capacity of Biopolymers by the Mechanochemical Activation

2012 ◽  
Vol 326-328 ◽  
pp. 504-508
Author(s):  
Svetlana Lugovskoy ◽  
Michael Zinigrad ◽  
Moshe Eliaszade
Keyword(s):  
Hydrogen Bond ◽  
Ir Spectroscopy ◽  
Functional Groups ◽  
Sorption Capacity ◽  
Mechanochemical Activation ◽  
Activation Process ◽  
Structure Deformation ◽  
Developed Surface ◽  
Load Release ◽  
Activation Times

Mechanochemical activation (MCA) of electrode lignin was performed and the activated lignin was studied by IR-spectroscopy for different activation times. The activated lignin was tested for the ability of binding Cr2O72-, Cu2+, Ni2+ ions. It was established that structure deformation, which does not distort the stronger hydrogen bond lattice, but leads to the formation of highly developed surface with active functional groups, occurs in the course of MCA. Weaker inter-layer bonds are broken in the activation process and quickly recovered after the load release. The comparison of the sorption capacity of Cr2O72-, Cu2+, Ni2+ ions by the MCA treated vs. inactivated lignin for different activation times was performed.

SEM and Auger microanalysis studies of Cu-Be dynode surfaces at each activation condition

1978 ◽  
Vol 36 (1) ◽  
pp. 524-525
Author(s):  
T. Koshikawa ◽  
Y. Fujii ◽  
E. Sugata ◽  
F. Kanematsu
Keyword(s):  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Life Time ◽  
Activation Process ◽  
Beam Diameter ◽  
Activation Temperature ◽  
Electron Multiplier ◽  
Activation Condition ◽  
Activation Conditions

The Cu-Be alloys are widely used as the electron multiplier dynodes after the adequate activation process. But the structures and compositions of the elements on the activated surfaces were not studied clearly. The Cu-Be alloys are heated in the oxygen atmosphere in the usual activation techniques. The activation conditions, e.g. temperature and O2 pressure, affect strongly the secondary electron yield and life time of dynodes.In the present paper, the activated Cu-Be dynode surfaces at each condition are investigated with Scanning Auger Microanalyzer (SAM) (primary beam diameter: 3μmϕ) and SEM. The commercial Cu-Be(2%) alloys were polished with Cr2O3 powder, rinsed in the distilled water and set in the vacuum furnance.Two typical activation condition, i.e. activation temperature 730°C and 810°C in 5x10-3 Torr O2 pressure were chosen since the formation mechanism of the BeO film on the Cu-Be alloys was guessed to be very different at each temperature from the results of the secondary electron emission measurements.

The Binding of Calcium Ions to Bovine Factor X by Rate Dialysis

1978 ◽  
Vol 40 (02) ◽  
pp. 350-357
Author(s):  
Robert H Yue ◽  
Menard M Gertler
Keyword(s):  
Molecular Weight ◽  
Dissociation Constant ◽  
Calcium Ions ◽  
Activation Process ◽  
Factor X ◽  
The Real ◽  
High Affinity ◽  
Binding Data ◽  
Sequential Mechanism ◽  
Bovine Factor

SummaryThe binding of Ca+2 to bovine factor X (molecular weight of 74,000) (Yue und Gertler 1977) was studied by the technique of rate dialysis and with the use of 45Ca+2. The binding data are consistent with a model of sequential mechanism. One mole of Ca+2 binds to the glycoprotein with a dissociation constant of 5.2 × 10-5 M and an additional 39 ± 4 moles of Ca+2 bind to this zymogen with a dissociation constant of 3.7 × 10-3M. The binding of the high affinity Ca+2 causes a functionally significant change in the zymogen, and (calcium) (factor X) complex is the real substrate in the activation process by the protease in Russell’s viper venom.

scholarly journals Computer Analysis of the Effect of Activation Temperature on the Microporous Structure Development of Activated Carbon Derived from Common Polypody

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2951
Author(s):  
Mirosław Kwiatkowski ◽  
Jarosław Serafin ◽  
Andy M. Booth ◽  
Beata Michalkiewicz
Keyword(s):  
Activated Carbon ◽  
Porous Structure ◽  
Computer Analysis ◽  
Density Functional ◽  
Activated Carbons ◽  
Chemical Activation ◽  
Geometrical Parameters ◽  
Activation Process ◽  
Microporous Structure ◽  
Activation Temperature

This paper presents the results of a computer analysis of the effect of activation process temperature on the development of the microporous structure of activated carbon derived from the leaves of common polypody (Polypodium vulgare) via chemical activation with phosphoric acid (H3PO4) at activation temperatures of 700, 800, and 900 °C. An unconventional approach to porous structure analysis, using the new numerical clustering-based adsorption analysis (LBET) method together with the implemented unique gas state equation, was used in this study. The LBET method is based on unique mathematical models that take into account, in addition to surface heterogeneity, the possibility of molecule clusters branching and the geometric and energy limitations of adsorbate cluster formation. It enabled us to determine a set of parameters comprehensively and reliably describing the porous structure of carbon material on the basis of the determined adsorption isotherm. Porous structure analyses using the LBET method were based on nitrogen (N2), carbon dioxide (CO2), and methane (CH4) adsorption isotherms determined for individual activated carbon. The analyses carried out showed the highest CO2 adsorption capacity for activated carbon obtained was at an activation temperature of 900 °C, a value only slightly higher than that obtained for activated carbon prepared at 700 °C, but the values of geometrical parameters determined for these activated carbons showed significant differences. The results of the analyses obtained with the LBET method were also compared with the results of iodine number analysis and the results obtained with the Brunauer–Emmett–Teller (BET), Dubinin–Radushkevich (DR), and quenched solid density functional theory (QSDFT) methods, demonstrating their complementarity.

scholarly journals Cold-induction of afadin in brown fat supports its thermogenic capacity

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Morten Lundh ◽  
Ali Altıntaş ◽  
Marco Tozzi ◽  
Odile Fabre ◽  
Tao Ma ◽  
...  
Keyword(s):  
Cold Exposure ◽  
Functional Enrichment ◽  
Activation Process ◽  
Target Tissue ◽  
Cold Stimulation ◽  
Brown Adipocytes ◽  
Protein Levels ◽  
Mrna Induction ◽  
Metabolic Functions ◽  
Brown Adipose

AbstractThe profound energy-expending nature of brown adipose tissue (BAT) thermogenesis makes it an attractive target tissue to combat obesity-associated metabolic disorders. While cold exposure is the strongest inducer of BAT activity, the temporal mechanisms tuning BAT adaptation during this activation process are incompletely understood. Here we show that the scaffold protein Afadin is dynamically regulated by cold in BAT, and participates in cold acclimation. Cold exposure acutely increases Afadin protein levels and its phosphorylation in BAT. Knockdown of Afadin in brown pre-adipocytes does not alter adipogenesis but restricts β3-adrenegic induction of thermogenic genes expression and HSL phosphorylation in mature brown adipocytes. Consistent with a defect in thermogenesis, an impaired cold tolerance was observed in fat-specific Afadin knockout mice. However, while Afadin depletion led to reduced Ucp1 mRNA induction by cold, stimulation of Ucp1 protein was conserved. Transcriptomic analysis revealed that fat-specific ablation of Afadin led to decreased functional enrichment of gene sets controlling essential metabolic functions at thermoneutrality in BAT, whereas it led to an altered reprogramming in response to cold, with enhanced enrichment of different pathways related to metabolism and remodeling. Collectively, we demonstrate a role for Afadin in supporting the adrenergic response in brown adipocytes and BAT function.

scholarly journals UV/Vis-Based Persulphate Activation for p-Nitrophenol Degradation

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 480
Author(s):  
Valentin Dubois ◽  
Carmen S. D. Rodrigues ◽  
Ana S. P. Alves ◽  
Luis M. Madeira
Keyword(s):  
Reaction Time ◽  
Oxidation Process ◽  
Activation Process ◽  
Direct Photolysis ◽  
Simulated Solar Light ◽  
Uv Visible ◽  
Oxidation Efficiency ◽  
Nitrophenol Degradation ◽  
Persulphate Oxidation ◽  
Radiation Type

In the present work, the degradation of p-nitrophenol (PNP) and its mineralization by a UV/Vis-based persulphate activation process was investigated. Firstly, a screening of processes as direct photolysis, persulphate alone and persulphate activated by radiation was performed. The incidence of radiation demonstrated to have an important role in the oxidant activation, allowing to achieve the highest PNP and total organic carbon (TOC) removals. The maximum PNP oxidation (100%) and mineralization (61.6%)—both after 2 h of reaction time—were reached when using T = 70 °C, (S2O82−) = 6.4 g/L and I = 500 W/m2. The influence of radiation type (ultraviolet/visible, visible or simulated solar light) was also evaluated, being found that the source with the highest emission of ultraviolet radiation (UV/visible) allowed to achieve the best oxidation efficiency; however, solar radiation also reached very-good performance. According to quenching experiments, the sulphate radical is key in the activated persulphate oxidation process, but the hydroxyl radical also plays an important role.

scholarly journals DYNAMICS IMPORTANCE SAMPLING FOR THE COLLECTION OF SWITCHING EVENTS IN VERTICAL-CAVITY SURFACE-EMITTING LASERS

2004 ◽  
Vol 04 (04) ◽  
pp. L635-L641
Author(s):  
STEFANO BERI ◽  
PETER V. E. McCLINTOCK ◽  
RICCARDO MANNELLA
Keyword(s):  
Importance Sampling ◽  
Numerical Approach ◽  
Cavity Surface ◽  
Activation Process ◽  
Polarization Switch ◽  
Surface Emitting Lasers ◽  
Vertical Cavity Surface ◽  
Emitting Lasers ◽  
Vertical Cavity ◽  
Qualitative Changes

A numerical approach based on dynamic importance sampling (DIMS) is applied to investigate polarization switches in vertical-cavity surface-emitting lasers. A polarization switch is described as an activation process in a two-dimensional nonequilibrium system. DIMS accelerates the simulations and allows access to noise intensities that were previously forbidden, revealing qualitative changes in the shape of the transition paths with noise intensity.

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